Radiator Advice

[Wes]

Somehow or other I now find an E28 M535i in my shed.
The car is a runner but needs work - don't they all.
Anyway it seems that replacement radiators are hard to source in Australia, and importing isn't looking cheap. My radiator seems structurally fine but just isn't getting the flow as it's full of gunk. Took it to the local radiator guy who told me to bin it and get a new one. He then attempted to order me one and couldn't!
Suggested giving it a bath and he wasn't excited at the idea. Obviously he had too much work!

Anyway I'm wondering if we know any tips for cleaning these things? I'm thinking perhaps fill with CLR and let sit, then flush? Or perhaps with caustic and do the same? Had good results with caustic on the past on fuel tanks thanks to an old radiator mechanic's tip off. He also said it works on radiators.

Seems every mechanic my age or younger these days isn't actually interested in repairing anything. They just seem to be glorified pit crew that swap out disposable crap, for more crap.

I need an @sfdon down here. Wonder if he'd do remote training for me? I'd like to think I'm enigmatic enough for the job...

 

[rsporsche]

here in the USA, there are old school radiator shops ... not near as many as there used to be ... but they would clean out the tanks, put a new core in ... then pressure test them. very few mechanics ever did that kind of work, but the radiator shops were invaluable.

 

[Wes]

here in the USA, there are old school radiator shops ... not near as many as there used to be ... but they would clean out the tanks, put a new core in ... then pressure test them. very few mechanics ever did that kind of work, but the radiator shops were invaluable.

We have a few of those left here. issue is the ends are crimped, not soldered so re-coring not an option.

 

[Thomas76]

Ultrasonic cleaning exists for jewelry, wonder if someone figured out car parts?

 

[Krzysztof]

You could try to flush it with some radiator cleaning fluid.

There are some on the market.

But you need to check with the supplier if it works for copper/brass soldered type.

I was using such chemistry in the past but not for E9 but aluminum radiator.
It was cleaning all the water passages in the engine.
First you are adding this to the cooling system and making it heat up till the thermostat will open and than wait 10-15 minutes.
Later on you need to flush it with water changing it few time till it will be clean after draining.
In the end fill the system with fresh cooling fluid.

Just an option to consider

 

[tochi]

It is difficult to evaluate "full of gunk." I received similar advice offered as a follow up to a blown head gasket. Repeated radiator flushing with a garden hose and plain water seemed to do the trick - since the same '72 original radiator is still being used in the same car without any overheating issues. Obviously, "your mileage may vary," but it is hard to see the downside of such an exercise, unless your radiator is leaking, not holding pressure or will not permit coolant flow. "Gunk" in your radiator is likely to reside toward the bottom, in which case, it might be a fair idea to remove the unit from the vehicle and reverse flush it upside down or any other means of disturbing and removing the "gunk." Where a more aggressive flush is indicated there are several "radiator" flushes available that might be worth a try. Best of luck.

 

[Wes]

Just an update. Pulled the radiator from the car and plugged the hose ends and laid it flat. Then filled with white vinegar and let sit for three days out in the sun.
Drained it yesterday and all manner of nastiness came flooding out. This happened again when I flushed it with a hose. Looking inside the thing it looks a lot cleaner, the bits I can see anyway. Obviously rodding or re-coring is the traditional route here but this radiator is a mix of plastic and crimped fittings. It's also OEM, so would be nice to save it.
Going to give it a second go with fresh vinegar and then reinstall after the spare parts arrive. Stay tuned.